Electric blower and vacuum cleaner equipped with same

Abstract

To provide an electric blower in which efficiency of a blower is high in a wide air volume range and in which cooling efficiency of a motor is also high, while it is small and light-weight.SOLUTION: A motor part includes a rotary shaft, a bearing, a rotor core, a stator core, and a motor housing in which an upstream side radial direction opening and a downstream side radial direction opening are opened on a side surface. A blower part includes: an impeller fixed to a tip of the rotary shaft; a fan casing for covering an outer periphery of the impeller; an upstream side housing for surrounding an upstream side outer periphery of the motor part; and a downstream side housing for surrounding a downstream side outer periphery of the motor part. A first flow passage circulates between an inner wall and an outer wall of the upstream side housing, and between an inner wall and an outer wall of the downstream side housing. A second flow passage circulates in the downstream side radial direction opening or in an opening in the rotary shaft direction of the downstream side motor housing, inside the motor part, the upstream side radial direction opening, between the motor housing and the inner wall of the upstream side housing, and between the motor housing and the inner wall of the downstream side housing. On the downstream side of the downstream side housing, an annular diffuser opposing to the downstream side radial direction opening is provided.SELECTED DRAWING: Figure 1B

Description

[Technical field]

[0001] The present invention relates to an electric blower and a vacuum cleaner equipped with the same. [Background technology]

[0002] As an example of an electric blower (blower device) built into an electric vacuum cleaner, Patent Document 1 describes a blower device comprising "an impeller 10 that rotates around a central axis C that extends vertically, a motor 20 that is positioned below the impeller and has a stator 24 to rotate the impeller, a motor housing 21 that houses the stator, and a fan casing 2 that houses the impeller and the motor housing and defines a first flow path 5 in the gap between the motor housing and the motor housing, the upper part of the fan casing covers the upper side of the impeller and has an intake port 3 that opens in the vertical direction, the lower part of the fan casing has an exhaust port 4 that communicates with the intake port via the first flow path, the motor housing has an inlet 21a that penetrates radially below the upper surface of the stator fixed to the inner surface of the motor housing and communicates with the first flow path, and the motor housing has a second flow path 6 that extends upward from the inlet and communicates with the space above the stator." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-105269 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that the operating air volume of a vacuum cleaner varies greatly depending on the operating conditions, such as the clogging of the filter due to dust, the material of the floor to be cleaned, etc. Therefore, there is a demand for an electric blower for a vacuum cleaner that has strong suction power over a wide range of air volumes.

[0005] In addition, to improve the usability of vacuum cleaners, there is a demand for smaller and lighter electric blowers. However, this reduces the heat dissipation area of ​​the electric blower and increases the heat density inside the electric blower, making it necessary to improve the cooling performance of the motor and bearings.

[0006] In particular, battery-powered (secondary battery) vacuum cleaners such as cordless stick vacuum cleaners and autonomous vacuum cleaners (robot vacuum cleaners) have low power consumption and small maximum airflow due to the battery capacity. This poses the issue that the dirt-transporting ability decreases when the filter becomes clogged, reducing the suction power of the vacuum cleaner. Furthermore, battery-powered vacuum cleaners are required to be small and lightweight, and the electric blowers installed in vacuum cleaners are required to have strong suction power over a wide range of airflows while also being compact.

[0007] Here, if a diffuser vane (referred to as "static vane 40" in Patent Document 1) is used, excellent pressure recovery can be achieved at the design point air volume. However, if the air volume falls below the design point air volume due to factors such as filter clogging, the diffuser performance will decrease due to a mismatch between the inlet angle of the diffuser vane and the inlet angle of the air flow into the diffuser, and the suction power of the vacuum cleaner may decrease.

[0008] In the blower of Patent Document 1, as shown in FIG. 4 and the like in the document, a part of the airflow S flowing through the outer first flow passage 5 flows into the inner second flow passage 6 through the inlet 21a provided in the peripheral wall of the motor housing 21, cools the upper bearing 26, and then cools the lower bearing 26. The airflow S is then exhausted to the outside of the blower 1 from the outlet (outlet 29a) of the second flow passage 6 without merging with the first flow passage 5. In this way, when the second flow passage 6 branched from the first flow passage 5 does not merge with the first flow passage 5, the pressure loss (resistance) generated when a part of the airflow S flowing through the first flow passage 5 branches into the second flow passage 6 causes a decrease in the airflow volume downstream of the inlet 21a (branching point) in the first flow passage 5 compared to the airflow volume upstream of the inlet 21a (branching point).

[0009] In addition, the second flow path 6 in Patent Document 1 is small in size, and therefore has a small flow path area. Furthermore, since the flow path bends inside the motor 20, there is a concern that the pressure loss in the flow path will be large, the amount of cooling air will be reduced, the temperature inside the motor 20 will be high, and the motor efficiency will be reduced.

[0010] The present invention is devised to solve the above-mentioned problems, and aims to provide an electric blower that is small and lightweight, yet has high blower efficiency over a wide range of air volumes and high motor cooling efficiency, and an electric vacuum cleaner equipped with the same. [Means for solving the problem]

[0011] In order to achieve the above object, the electric blower of the present invention is an electric blower in which a first flow path flows inside a blower section and a second flow path flows inside a motor section, the motor section includes a rotating shaft, a bearing for rotatably supporting the rotating shaft, a rotor core fixed to the rotating shaft, a stator core arranged to surround an outer periphery of the rotor core, and a motor housing for holding the stator core and having an upstream radial opening and a downstream radial opening on a side surface, and the blower section includes an impeller fixed to a tip of the rotating shaft, a fan casing covering the outer periphery of the impeller, and an upstream housing surrounding the upstream outer periphery of the motor section. the first flow path passes between the inner wall and the outer wall of the upstream housing and between the inner wall and the outer wall of the downstream housing, the second flow path passes through the downstream radial opening, the opening in the rotational axis direction of the downstream motor housing, the inside of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and between the motor housing and the inner wall of the downstream housing, and a circular diffuser is provided on the downstream side of the downstream housing facing the downstream radial opening. Effect of the Invention

[0012] According to the present invention, it is possible to provide an electric blower that is small and lightweight, yet has high blower efficiency over a wide range of air volumes and high motor cooling efficiency, and an electric vacuum cleaner equipped with the same. [Brief description of the drawings]

[0013] [Figure 1A] 1 is an external view of an electric blower according to an embodiment; [Figure 1B] 1 is a vertical cross-sectional view of an electric blower according to an embodiment; [Figure 2A] FIG. 2 is a perspective view of an impeller according to an embodiment. [Figure 2B] FIG. 2 is a longitudinal sectional view of an impeller according to an embodiment. [Figure 3A] FIG. 4 is a top view of an upstream housing of one embodiment. [Figure 3B] FIG. 4 is a vertical cross-sectional view of an upstream housing according to an embodiment. [Figure 3C] FIG. 4 is a partial cross-sectional view of an embodiment of an upstream housing. [Figure 4A] FIG. 4 is a top view of the downstream housing of one embodiment. [Figure 4B] FIG. 4 is a vertical cross-sectional view of a downstream housing of an embodiment. [Figure 4C] FIG. 2 is a partial cross-sectional perspective view of an embodiment of a downstream housing. [Figure 5A] FIG. 2 is an external view of a motor unit according to an embodiment. [Figure 5B] FIG. 2 is a vertical cross-sectional view of a motor unit according to an embodiment. [Figure 6A] FIG. 4 is a vertical cross-sectional view showing an example of the structure of a second flow path. [Figure 6B] FIG. 4 is a vertical cross-sectional view showing an example of the structure of a second flow path. [Figure 6C] FIG. 4 is a vertical cross-sectional view showing an example of the structure of a second flow path. [Figure 6D] FIG. 4 is a vertical cross-sectional view showing an example of the structure of a second flow path. [Figure 7] FIG. 1 is a perspective view of a vacuum cleaner according to an embodiment. [Figure 8] FIG. 1 is a vertical cross-sectional view of a vacuum cleaner according to an embodiment. [Figure 9] 6 is a graph comparing the blower efficiency of the electric blower of the embodiment and the comparative example. [Figure 10]4 is a graph comparing temperature rises of an electric blower according to an embodiment and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric blower and an electric vacuum cleaner including the same according to the present invention will be described in detail below with reference to the drawings.

[0015] <General Configuration of Vacuum Cleaner 100> First, a vacuum cleaner 100 according to an embodiment of the present invention will be described with reference to Figures 7 and 8. Figure 7 is a perspective view of the vacuum cleaner 100, and Figure 8 is a vertical cross-sectional view of the vacuum cleaner 100. The vacuum cleaner 100 shown in the figure is a rechargeable cordless stick vacuum cleaner in which the cleaner body 110 is attached to a holder 120, and can be charged while placed on a charging stand 130. Note that, although a rechargeable cordless stick vacuum cleaner is shown as an example here, the electric blower 200 of the present invention may be built into a non-rechargeable stick vacuum cleaner equipped with a power cord.

[0016] The vacuum cleaner body 110 is a unit that can be used alone as a handheld vacuum cleaner, and is provided with a body grip part 111 at the top that the user holds when using it as a handheld vacuum cleaner, and a suction port opening 112 at the bottom that sucks in dust when using it as a handheld vacuum cleaner. The inside of the vacuum cleaner body 110 is provided with a dust collection chamber 113 that collects dust, an electric blower 200 that generates the suction airflow required for dust collection, a drive circuit 114 that drives the electric blower 200, and a battery unit 115 that supplies power to the drive circuit 114.

[0017] On the other hand, the holding part 120 is a unit to which the vacuum cleaner body 110 can be attached and detached, and is provided at its upper part with a grip part 121 that is held by the user when using it as a stick vacuum cleaner, and at its lower part with a suction body 122 that sucks up dust when using it as a stick vacuum cleaner, and a connection part 122a that connects the suction body 122 to the intake opening 112.

[0018] In addition, the main body grip portion 111 of the vacuum cleaner main body 110 is provided with a main body switch portion 111a for turning on / off the power of the electric blower 200 when used as a handheld vacuum cleaner, and the grip portion 121 of the holding portion 120 is provided with a switch portion 121a for turning on / off the power of the electric blower 200 when used as a stick vacuum cleaner.

[0019] <Electric blower 200> Next, electric blower 200 of this embodiment will be described in detail with reference to Figures 1A to 6, 9 and 10. Electric blower 200 of this embodiment mainly has an impeller 1, a rotating shaft 2, a fan casing 3, an upstream housing 4, a downstream housing 5, an upstream motor housing 6, a downstream motor housing 7, upstream diffuser blades 8, and downstream diffuser blades 9, which constitute a blower section 201 and a motor section 202.

[0020] FIG. 1A is an external view of electric blower 200, and FIG. 1B is a vertical cross-sectional view of electric blower 200. Electric blower 200 of this embodiment is a blower that draws in air from upper intake port 200a and expels air from lower exhaust port 200b when impeller 1 is rotated, so that the upstream side and downstream side are defined as shown in the figure. In addition, focusing on the installation direction of rotating shaft 2, axial direction and radial direction are defined as shown in the figure. Note that electric blower 200 is installed inside electric vacuum cleaner 100 with intake port 200a of electric blower 200 facing downward and exhaust port 200b facing upward so that dust can be sucked up from suction port body 122 at the bottom of electric vacuum cleaner 100 to dust collection chamber 113 at the top (see FIG. 8).

[0021] 1A, the outer periphery of electric blower 200 is covered by an outer shell that integrates fan casing 3, upstream housing 4, and downstream housing 5. A specific method for integrating these will be described later.

[0022] 1B, a rotating shaft 2 is rotatably disposed inside electric blower 200, and impeller 1 is fixed to the upper end thereof, rotating integrally with rotating shaft 2. Note that, in FIG. 1B, impeller 1 is fixed by a nut screwed onto the upper end of rotating shaft 2, but impeller 1 may also be fixed by press-fitting onto the tip of rotating shaft 2.

[0023] When the impeller 1 rotates, an air flow path indicated by a solid arrow in the figure (hereinafter referred to as a "first flow path F1") that flows through the blower section 201 from the intake port 200a toward the exhaust port 200b, and an air flow path indicated by a dotted arrow in the figure (hereinafter referred to as a "second flow path F2") that branches off downstream of the first flow path F1 and flows from downstream to upstream in the motor section 202 are formed inside the electric blower 200, as shown in the left side of Fig. 1B. Hereinafter, the structure of the electric blower 200 of this embodiment, which allows a desired air flow to flow through the first flow path F1 and the second flow path F2 and can sufficiently cool the inside of the motor section 202 while maintaining suction force over a wide range of airflow, will be described in order, with the blower section 201 and the motor section 202 being separated.

[0024] <Blower section 201> Blower section 201 is a unit for generating an airflow that sucks up dust in vacuum cleaner 100, and as shown in Fig. 1B, from the upstream side, there are arranged an impeller 1 which is a rotor, an upstream diffuser vane 8 provided on the inner circumference of upstream housing 4, a downstream diffuser vane 9 provided on the inner circumference of downstream housing 5, and the like. Note that in this embodiment, upper and lower diffuser vanes are provided to control the flow speed of the airflow downstream of impeller 1 and to control the static pressure, but as long as the Venturi effect described below can be sufficiently maintained, some or all of the diffuser vanes may be omitted. Each section will be described below in order.

[0025] <Impeller 1 and fan casing 3> First, the impeller 1 will be described with reference to Figures 2A and 2B. Figure 2A is a perspective view of the impeller 1, and Figure 2B is a vertical cross-sectional view of the impeller 1. The impeller 1 in both figures is an open-type mixed-flow impeller without a shroud plate, and has a hub 11, a plurality of blades 12, and a boss 13 for inserting the rotating shaft 2, which are integrally molded from engineering plastic or thermoplastic resin. The impeller 1 of this embodiment may be a mixed-flow impeller with a shroud plate, or may be a centrifugal impeller or an axial flow impeller.

[0026] A metallic sleeve 14 is provided as an integrally molded product on the back side of the hub 11, coaxially with the boss 13 of the impeller 1. By using such a sleeve 14, it is possible to reduce the variation in the fit gap between the impeller 1 and the rotating shaft 2, which is highly likely to occur when no sleeve is used, and to reduce imbalance of the impeller 1, thereby reducing vibration and noise when the impeller 1 is driven to rotate. In addition, a protrusion 14a is provided on the downstream side of the sleeve 14. The function of this protrusion 14a will be described later.

[0027] The fan casing 3 is a cover that covers the outer periphery of the impeller 1 and is integrally molded from engineering plastic or thermoplastic resin. As shown in FIG. 1B, the fan casing 3 has an intake port 200a opening on the upstream side and also functions as a shroud plate for the impeller 1.

[0028] <Upstream housing 4 and upstream diffuser vane 8> Next, the upstream housing 4 and the upstream diffuser vane 8 will be described with reference to Fig. 3A to Fig. 3C. Fig. 3A is a plan view of the upstream housing 4 as viewed from the upstream side, Fig. 3B is a vertical cross-sectional view of the upstream housing 4, and Fig. 3C is a partial cross-sectional view of the upstream housing 4 as viewed from the outer periphery. Note that Fig. 3C shows the shape of the upstream diffuser vane 8 (particularly the positions of the leading edge 8a and the trailing edge 8b) by partially omitting the shroud of the upstream housing 4.

[0029] The upstream housing 4 and the upstream diffuser vanes 8 are integrally molded from engineering plastic or thermoplastic resin, and as shown in Figures 3A to 3C, a plurality of upstream diffuser vanes 8 integrally molded with the inner wall 4a (hub) and outer wall 4b (shroud) of the upstream housing 4 are arranged at equal intervals in the circumferential direction between them.

[0030] The length (chord length) from the leading edge 8a to the trailing edge 8b of the upstream diffuser vane 8 is longer on the outer wall 4b side than on the inner wall 4a side. This is because, downstream of the impeller 1, the wind speed on the outer circumferential side is faster than on the inner circumferential side, so by making the outer side of the upstream diffuser vane 8 longer than the inner side, it is possible to suppress losses and improve the efficiency of the blower. Note that, although a configuration with 15 upstream diffuser vanes 8 is shown here as an example, the number of upstream diffuser vanes 8 can be changed depending on the specifications of the electric blower 200.

[0031] Furthermore, as shown in Figures 3A and 3C, protrusions 4c are provided at three equally spaced locations on the outer periphery of the outer wall 4b of the upstream housing 4, and the claw portions 5c of the downstream housing 5, which will be described later, are fitted into these protrusions, allowing the upstream housing 4 and the downstream housing 5 to be integrated while being centered (see Figure 1B).

[0032] As shown in FIGS. 3A and 3B, fastening portions 4d are provided at two locations on the upper surface of the upstream housing 4, and the motor portion 202 can be fastened to these portions while being centered (see FIG. 1B).

[0033] Furthermore, as shown in Figures 3A to 3C, a fitting portion 4e is provided on the outer periphery of the outer wall 4b of the upstream housing 4 other than the protrusion 4c, and by fitting the lower end of the fan casing 3 into this fitting portion and adhesively fixing it, the fan casing 3 and the upstream housing 4 can be integrated while being centered (see Figure 1B).

[0034] <Downstream housing 5 and downstream diffuser vane 9> Next, the downstream housing 5 and the downstream diffuser vane 9 will be described with reference to Fig. 4A to Fig. 4C. Fig. 4A is a plan view of the downstream housing 5 as viewed from the upstream side, Fig. 4B is a vertical cross-sectional view of the downstream housing 5, and Fig. 4C is a partially cross-sectional perspective view of the downstream housing 5 as viewed from the outer periphery. Note that Fig. 4C shows the shape of the downstream diffuser vane 9 (particularly the positions of the leading edge 9a and the trailing edge 9b) by partially omitting the shroud of the downstream housing 5.

[0035] The downstream housing 5 and the downstream diffuser vanes 9 are integrally molded from engineering plastic or thermoplastic resin, and as shown in Figures 4A to 4C, a plurality of downstream diffuser vanes 9 integrally molded with the inner wall 5a (hub) and outer wall 5b (shroud) of the downstream housing 5 are disposed at equal intervals in the circumferential direction between them. Note that, although a configuration in which 15 downstream diffuser vanes 9 are provided is illustrated here, this is because the number of upstream diffuser vanes 8 and downstream diffuser vanes 9 are made to match in order to arrange the downstream diffuser vanes 9 downstream of each upstream diffuser vane 8.

[0036] 4A to 4C, the downstream housing 5 has three equally spaced claws 5c on the outer periphery of the upper end, and a fitting portion 5d is provided on the outer periphery of the upper end excluding the claws 5c. By pressing the lower end of the upstream housing 4 against the fitting portion 5d of the downstream housing 5 and fitting the three claws 5c into the three protrusions 4c, the upstream housing 4 and the downstream housing 5 can be integrated while being centered (see FIG. 1B).

[0037] 4B and 4C, an annular diffuser 5e not provided with a downstream diffuser vane 9 is provided downstream of the downstream housing 5. The details of this annular diffuser 5e will be described later.

[0038] Here, as shown in FIG. 1B, in this embodiment, the inner wall 4a of the upstream housing 4 and the inner wall 5a of the downstream housing 5, and the outer wall 4b of the upstream housing 4 and the outer wall 5b of the downstream housing 5 are integrated while being approximately aligned in the radial direction. This makes the inner surface of each flow passage smooth, and reduces loss in each flow passage. In addition, in this embodiment, the circumferential positions of the trailing edge 8b of the upstream diffuser vane 8 and the leading edge 9a of the downstream diffuser vane 9 are aligned, and the curved surfaces of the upstream diffuser vane 8 and the downstream diffuser vane 9 are smoothly continuous, so that a pair of the upstream diffuser vane 8 and the downstream diffuser vane 9 function as one diffuser vane. Furthermore, in this embodiment, the thickness of each diffuser vane is made thicker from the upstream side to the downstream side, thereby increasing the static pressure and realizing high efficiency of the blower unit 201.

[0039] <Motor section 202> Next, the motor section 202 will be described with reference to Figures 5A and 5B. Figure 5A is a side external view of the motor section 202, and Figure 5B is a vertical cross-sectional view of the motor section 202. The illustrated motor section 202 is a unit for rotating the impeller 1 of the blower section 201 within a range of, for example, 50,000 to 200,000 [rpm], and is composed of a rotating shaft 2, an upstream bearing 21, a downstream bearing 22, a rotor core 23, a stator core 24, a collar 25, an upstream motor housing 6, a downstream motor housing 7, etc. Each section will be described in order below.

[0040] <Housing of motor unit 202> As shown in both figures, motor section 202 has an upstream motor housing 6 and a downstream motor housing 7 as housings for holding stator core 24 and the like, and by fixing the upper surface of upstream motor housing 6 to the lower surface of upstream housing 4 with screws or the like, motor section 202 can be built into electric blower 200 (see FIG. 1B).

[0041] The upstream motor housing 6 is a metal (aluminum alloy, steel, etc.) housing that covers the upstream side of the motor section 202, and has a plurality of (for example, six) radial openings 6a on its side as shown in Fig. 5A. As shown in Fig. 5B, the center of the upper surface of the upstream motor housing 6 protrudes upward, and an upstream bearing 21 that rotatably supports the upstream side of the rotating shaft 2 is provided inside the protrusion. The upstream bearing 21 is positioned in the axial direction by an upstream spacer 21a below the upstream bearing 21. An axial opening may be provided in the upstream motor housing 6, and in that case, cooling air can flow to the bearing 21 to cool it.

[0042] On the other hand, the downstream motor housing 7 is a metal (aluminum alloy, steel, etc.) housing that covers the downstream side of the motor section 202, and has multiple (e.g., six) radial openings 7a on its side and multiple axial openings 7b on its bottom surface, as shown in Fig. 5A. Also, as shown in Fig. 5B, the center of the bottom surface of the downstream motor housing 7 protrudes downward, and a downstream bearing 22 that rotatably supports the downstream side of the rotating shaft 2 is provided inside the protrusion. The downstream bearing 22 is positioned in the axial direction by a downstream spacer 22a above the downstream bearing 22.

[0043] As shown in FIG. 5A, in this embodiment, the upstream radial opening 6a and the downstream radial opening 7a are arranged so as not to overlap in the axial direction. The radial openings 6a and 7a of each motor housing are arranged so as to overlap in the axial direction with the axial end of the coil 24b described later. The radial openings of each motor housing are arranged uniformly in the circumferential direction, and the number of openings and the number of diffuser vanes are set so that the greatest common divisor between the number of radial openings and the number of diffuser vanes is 3. As a result, the same flow field is formed at three points in the circumferential direction inside the motor section 202, so that the temperature distribution in the circumferential direction can be reduced. The number of radial openings and the number of diffuser vanes may be set to a predetermined value other than 3 as the greatest common divisor.

[0044] In this embodiment, in order to improve the cooling performance of motor section 202, each motor housing is made of metal to improve heat dissipation performance, and an area in which stator core 24 is exposed (exposed section 24a) is provided between the upper and lower motor housings so that stator core 24 can be cooled from the outside. However, in cases where the amount of heat generated by motor section 202 is relatively small, each motor housing may be made of heat-resistant resin, or the upper and lower motor housings may be connected to form a structure in which stator core 24 is not exposed.

[0045] Furthermore, while it is possible for the motor to be cooled using only the radial opening 7a and the axial opening 7b of the downstream motor housing 7, the presence of the axial opening 7b reduces the pressure loss when taking in motor cooling air, increases the amount of motor cooling air, and makes it possible to cool the motor.

[0046] <Rotor of the motor section 202> 5B, rotor core 23 is fixed to the rotating shaft 2 in a region sandwiched between upper and lower spacers. This rotor core 23 is a rotor of motor section 202 that incorporates rare earth bonded magnets such as samarium iron nitrogen magnets and neodymium magnets.

[0047] 5A, a collar 25 is fixed to the rotating shaft 2 protruding from the upper part of the upstream motor housing 6, and a recess 25a is provided on the upper part of the collar 25. By fitting this recess 25a into the protrusion 14a of the sleeve 14 of the impeller 1 described above, the torque of the rotating shaft 2 can be reliably transmitted to the impeller 1, and the impeller 1 can be prevented from spinning freely.

[0048] <Stator of the motor section 202> As shown in Fig. 5B, stator core 24, which is the stator of motor section 202, is disposed on the outer periphery of motor section 202 so as to surround rotor core 23, which is the rotor of motor section 202. Coil 24b, which is made of aluminum wire or copper wire covered with a coating material, is wound around the winding frame of stator core 24, and stator core 24 can be made into an electromagnet by supplying a desired AC power from drive circuit 114 in Fig. 8 to coil 24b, and rotor core 23, rotating shaft 2, and impeller 1 can be rotated integrally at high speed.

[0049] Furthermore, by driving an adhesive into the upstream side of the stator core 24 and fixing the upstream motor housing 6 to the downstream side, and driving an adhesive into the downstream side and fixing the downstream motor housing 7 to the downstream side, the stator core 24, the upstream motor housing 6, and the downstream motor housing 7 can be integrated.This allows a radial opening 6a to be provided in the upstream motor housing 6 at the height of the upstream end of the coil 24b, and a radial opening 7a to be provided in the downstream motor housing 7 at the height of the downstream end of the coil 24b.

[0050] <Structures of first flow path F1 and second flow path F2> Next, the structures of the first flow path F1 and the second flow path F2 of this embodiment will be described in detail with reference to FIG. 1B and FIG. 6A.

[0051] 1B, assuming that the dimensions defining the shapes of the first flow passage F1 and the second flow passage F2 are the radial height H1 of the downstream diffuser vane 9, the radial distance H2 between the inner surface of the annular diffuser 5e and the outer surface of the downstream motor housing 7, the axial length L1 of the inner wall 5a, the axial length L2 of the downstream diffuser vane 9, and the axial length L3 of the annular diffuser 5e, in the electric blower 200 of this embodiment, in order to simultaneously improve the blower efficiency of the blower section 201 and the cooling efficiency of the motor section 202, the functions of each formula will be described below with reference to FIG. 6A, which is an enlarged cross-sectional view of the right-side flow passage in FIG. 1B.

[0052] H1 ≧ 0.5×H2 (Formula 1) More preferably, H1 ≧ 0.66 × H2 (Equation 1′) 0.5×L2 ≦ L1 ≦ L2 (Formula 2) More preferably, L1 ≒ 0.5 × L2 (Equation 2') L3 ≧ 2.5×H1 (Formula 3) More preferably, L3 ≧ 3×H1 (Equation 3′) When electric power is supplied to motor section 202 to rotate impeller 1, a first flow path F1 through blower section 201 and a second flow path F2 mainly through motor section 202 are formed inside electric blower 200, as shown in Fig. 6A. Second flow path F2 branching off from first flow path F1 passes through the following flow paths (1) to (5), and is exhausted from exhaust port 200b of electric blower 200.

[0053] (1) First, the airflow branched from the first flow passage F1 inside the annular diffuser 5e flows into the inside of the motor section 202 through the downstream radial openings 7a and the axial openings 7b. In this embodiment, by arranging the annular diffuser 5e on the outer circumferential side of the downstream radial openings 7a, the airflow flowing out from the downstream diffuser vanes 9 is suppressed from diffusing in the outer circumferential direction, and the airflow branched from the first flow passage F1 can be efficiently guided into the inside of the motor section 202.

[0054] (2) The air flow that flows into the inside of the motor section 202 from the downstream radial opening 7a flows from the downstream side to the upstream side, efficiently cooling the downstream bearing 22, the rotor core 23, the stator core 24, the upstream bearing 21, etc., which are in a high temperature state.

[0055] (3) The air flow that flows upstream inside the motor section 202 flows out to the outside of the motor section 202 from the upstream radial opening 6a, and then flows downstream through the gap between the inner surface of the inner wall 4a of the upstream housing 4 and the outer surface of the upstream motor housing 6, further cooling the exposed portion 24a of the stator core 24.

[0056] (4) The airflow that has cooled the exposed portion 24a merges with the first flow passage F1 near the lower end of the inner wall 5a of the downstream housing 5. In this embodiment, as in (Formula 1) or (Formula 1'), the radial height H1 of the downstream diffuser vane 9 is set large, so that the downstream diffuser vane 9 can be brought closer to the downstream motor housing 7, and the flow velocity in the outer circumferential region of the downstream motor housing 7 can be increased. In addition, as in (Formula 2'), if the lower end of the inner wall 5a of the downstream housing 5 is located at a position that is approximately half the axial length of the downstream diffuser vane 9 (for example, L1 / L2=0.5 to 0.6), the second flow passage F2 can be merged with the first flow passage F1 in the region where the high-speed flow passing through the downstream diffuser vane 9 exists. Therefore, the Venturi effect of the high-speed first flow passage F1 can efficiently suck in air from the upstream radial opening 6a inside the motor section 202, and as a result, cooling air can efficiently be taken in from the downstream radial opening 7a and axial opening 7b into the negative pressure inside the motor section 202. In other words, the Venturi effect of the first flow passage F1 can improve the cooling efficiency of the motor section 202 regardless of the operating range of the electric blower 200.

[0057] (5) The airflow that merges with the first flow path F1 is exhausted from the exhaust port 200b. In this embodiment, as shown in (Equation 3) or (Equation 3'), an annular diffuser 5e is provided with an axial length L3 that corresponds to the radial height H1 of the downstream diffuser vane 9. Since the axial length L3 of the annular diffuser 5e is sufficiently longer than the radial height H1 of the downstream diffuser vane 9, a sudden expansion of the flow path downstream of the downstream diffuser vane 9 is suppressed, and as a result, the blowing efficiency of the blower section 201 is improved.

[0058] <Effects of the Annular Diffuser 5e> Next, the effects of the annular diffuser 5e of this embodiment will be described with reference to the experimental results in Figures 9 and 10. The comparative example shown in Figures 9 and 10 corresponds to an electric blower in which the annular diffuser 5e has been removed from electric blower 200 in Figure 6A.

[0059] In the electric blower of the comparative example, since there is no annular diffuser 5e at a position facing the downstream radial opening 7a, the flow path expands suddenly downstream of the trailing edge 9b of the downstream diffuser vane 9 through which the high-speed air flows. In this case, as shown in the experimental result of FIG. 9, the efficiency of the electric blower is significantly deteriorated compared to the electric blower 200 of this embodiment equipped with the annular diffuser 5e. Accordingly, in the electric blower of the comparative example, the amount of air flowing into the motor section 202 is reduced, and as shown in FIG. 10, the temperature of the bearings (upstream bearing 21, downstream bearing 22), stator core 24, coil 24b, etc. inside the motor section 202 is about 25 to 40 K higher than that of the electric blower 200 of this embodiment.

[0060] Therefore, as is clear from Figures 9 and 10, electric blower 200 of this embodiment equipped with annular diffuser 5e not only improves the blowing efficiency of blower section 201, but also improves the cooling efficiency of motor section 202, compared to the electric blower of the comparative example that does not have an annular diffuser.

[0061] <Modification> Next, a modification of the structure of FIG. 6A will be described with reference to FIGS. 6B to 6D.

[0062] In Fig. 6B, the downstream radial opening 7a is disposed further downstream than in Fig. 6A. In this case, the second flow path F2 branches off from the first flow path F1 near the position where the innermost airflow in the first flow path F1 shown by the solid line adheres to the downstream motor housing 7. This increases the amount of air drawn into the motor section 202 from the downstream radial opening 7a, thereby making it possible to further improve the cooling efficiency of the motor section 202 compared to Fig. 6A.

[0063] In Fig. 6C, the downstream radial opening 7a is disposed further upstream than in Fig. 6A. In this case, of the airflow in the first flow passage F1 shown by the solid line, the airflow on the innermost periphery side adheres to the outer circumferential surface of the downstream motor housing 7 further upstream, so that separation of the airflow in the region of the annular diffuser 5e where the flow passage expands can be suppressed, and the blowing efficiency of the blower section 201 can be further improved than in Fig. 6A.

[0064] In Fig. 6D, instead of the radial opening 7a and the axial opening 7b, a corner opening 7c that combines the functions of both is provided. In this case, the same effect as in Fig. 6B can be obtained with a simplified configuration.

[0065] 6A to 6D, the annular diffuser 5e is provided downstream of the downstream housing 5, but the annular diffuser 5e may be omitted. In that case, in order to prevent the flow passage of the first flow passage F1 from suddenly expanding in the vicinity of the downstream radial opening 7a, the downstream diffuser vane 9 should be extended at least to the axial position facing the downstream radial opening 7a.

[0066] In addition, the cooling by the Venturi effect of this configuration makes it possible to cool the motor even without diffuser vanes on the upstream housing and the downstream housing.

[0067] <Effects of this embodiment> According to the present embodiment described above, it is possible to provide an electric blower that is small and lightweight, yet has high blower efficiency over a wide range of air volumes and high motor cooling efficiency, and an electric vacuum cleaner equipped with the same.

[0068] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to easily explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0069] 100 Vacuum Cleaner 110 Vacuum cleaner body 111 Main body grip part 111a Main unit switch 112 Intake opening 113 Dust Collection Room 114 Drive circuit 115 Battery Unit 120 Holding part 121 Grip section 121a Switch section 122 Mouthpiece 122a Connection 130 Charging stand 200 electric blower 200a Intake 200b Exhaust port 201 Blower section 202 Motor section 1 Impeller 11. Hub 11a Hub protrusion 12 Feather 13. Boss 13a Boss surface 14 Sleeve 14a Convex part 2 Rotation Axis 21 Upstream bearing 21a Upstream spacer 22 Downstream bearing 22a Downstream spacer 23 Rotor core 24 Stator core 24a Exposed part 24b Coil 25 Color 25a Recess 3 Fan casing 4 Upstream housing 4a inner wall 4b Exterior wall 4c protrusion 4d fastening part 4e Fitting part 5 Downstream housing 5a Inner wall 5b Exterior wall 5c Claw part 5d Fitting part 5e Annular Diffuser 6 Upstream motor housing 6a radial opening 7 Downstream motor housing 7a radial opening 7b Axial opening 7c Corner opening 8 Upstream diffuser vane 8a Leading edge 8b Trailing edge 9 Downstream diffuser vane 9a Leading edge 9b Trailing edge F1 First flow path F2 Second flow path

Claims

1. An electric blower having a first flow path in a blower unit and a second flow path in a motor unit, the motor section includes a rotating shaft, a bearing that rotatably supports the rotating shaft, a rotor core fixed to the rotating shaft, a stator core arranged to surround an outer periphery of the rotor core, and a motor housing that holds the stator core and has an upstream radial opening and a downstream radial opening on a side surface, the blower unit includes an impeller fixed to a tip of the rotary shaft, a fan casing covering an outer periphery of the impeller, an upstream housing surrounding an outer periphery of the upstream side of the motor unit, and a downstream housing surrounding an outer periphery of the downstream side of the motor unit, the first flow passage extends between an inner wall and an outer wall of the upstream housing and between an inner wall and an outer wall of the downstream housing; the second flow passage passes through the downstream radial opening, the opening in the rotational axis direction of the downstream motor housing, the inside of the motor section, the upstream radial opening, between the motor housing and the inner wall of the upstream housing, and between the motor housing and the inner wall of the downstream housing; a downstream housing having a radial opening extending from the downstream housing to the downstream side of the downstream housing;

2. The electric blower according to claim 1, an upstream diffuser vane is provided between an inner wall and an outer wall of the upstream housing; a downstream diffuser vane provided between the inner wall and the outer wall of the downstream housing.

3. The electric blower according to claim 2, 1. An electric blower comprising: a downstream diffuser vane having a radial height H1 and a radial distance between an inner surface of the annular diffuser and an outer surface of the motor housing H2, the ... and the H1 ≧ 0.5×H2, H1 ≧ 0.66×H2

4. The electric blower according to claim 2, 1. An electric blower comprising: a downstream housing having an inner wall with an axial length of L1; and a downstream diffuser vane with an axial length of L2; the downstream housing having an inner wall with an axial length of L1; 0.5×L2 ≦ L1 ≦ L2, L1 ≒ 0.5 × L2

5. The electric blower according to claim 2, 1. An electric blower comprising: a downstream diffuser vane having a radial height of H1 and an annular diffuser having an axial length of L3, the downstream diffuser vane having a radial height of H1 and ... L3 ≧ 2.5×H1, L3≧3×H1

6. The electric blower according to claim 1, an electric blower, characterized in that the motor housing comprises an upstream motor housing covering the upstream side of the stator core and a downstream motor housing covering the downstream side of the stator core, and the second flow path flows along an exposed portion of the stator core that is not covered by the upstream motor housing and the downstream motor housing.

7. An electric blower having a first flow path in a blower unit and a second flow path in a motor unit, the motor section includes a rotating shaft, a bearing that rotatably supports the rotating shaft, a rotor core fixed to the rotating shaft, a stator core arranged to surround an outer periphery of the rotor core, and a motor housing that holds the stator core and has an upstream radial opening and a downstream radial opening on a side surface, the blower unit includes an impeller fixed to a tip of the rotary shaft, a fan casing covering an outer periphery of the impeller, an upstream housing surrounding an outer periphery of the upstream side of the motor unit, and a downstream housing surrounding an outer periphery of the downstream side of the motor unit, the first flow passage extends between an inner wall and an outer wall of the upstream housing and between an inner wall and an outer wall of the downstream housing; the second flow passage passes through the downstream radial opening, an interior of the motor portion, the upstream radial opening, a gap between the motor housing and an inner wall of the upstream housing, and a gap between the motor housing and an inner wall of the downstream housing; a downstream diffuser vane provided on the downstream side of the downstream housing so as to face the downstream radial opening,

8. The electric blower according to any one of claims 1 to 7, An electric blower having an axial opening in either an upstream or downstream motor housing or in both.

9. An electric vacuum cleaner comprising the electric blower according to any one of claims 1 to 8.

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